The top seed needed all his skill and fighting spirit to tame the eighth-seeded Del Potro who made light of his knee injury to keep the world number one on court for four hours 43 minutes, the longest semi-final ever seen at Wimbledon.

Djokovic broke in the 12th game of the first set to win it 7-5 but Del Potro took the Serbian's serve midway through the second set and levelled the match on a bakingCentre Court.

Del Potro saved three set points at 5-6 in the third but Djokovic stepped up his level to romp through the tiebreak 7-2.

The top seed struck again with a break in the seventh game of the fourth set but Del Potro broke straight back and saved two match points in an incredible tiebreak before taking it 8-6.

Djokovic broke again to lead 5-3 in the deciding set and he recovered from 0-30 down to seal victory with a searing backhand down the line.

Djokovic will play second seed Andy Murray or Jerzy Janowicz, seeded 24th, in the final on Sunday (July 7) when he will bid for his second Wimbledon title and seventh grand slam crown.